The normal operation of the foot provides a smooth rolling motion through a step when ambulating. In a normal gait, the load on a person's foot moves from heel to toe at an angle from the lateral side or outside of the foot (supination) to the medial side or inside of the foot (pronation). A normal step begins with the heel strike as the heel is set down on the support surface or ground and ends with the toe off as the large toe pushes the foot off the support surface.
Many efforts have been made over the years to construct an outsole for orthopedic devices that promotes a healthy and natural gait. One such outsole construction is tapered or curved directly from back to front in a linear fashion. Such a design initiates a roll-over that is limited to straight ahead from back to front allowing heel strike, rocking straight forward, then toe off. However, most people do not walk with their feet pointed straight ahead. Rather, most people walk with their feet externally rotated. When feet point outward, it is commonly called toed-out or exorotated. When feet point inward, it is commonly called toed-in, a tendency referred to as walking “pigeon toed.” Thus, because people do not walk with their feet straight forward, the linear roll-over motion of known outsoles resists the natural gait of the wearer's foot, adding stress and discomfort to the wearer as the wearer ambulates, which may adversely affect recuperation and/or cause undesirable biomechanical compensations which can cause problems for the wearer in the long term. Such problems can include, but are not limited to, bad posture, back problems, an unhealthy gait, foot abnormalities, muscle imbalances in the foot and/or leg, and/or pressure ulcers.
The linear roll-over motion of known outsoles also causes foot and leg fatigue because the action of the outsole conflicts with the natural roll-over motion of the user, requiring the user to adjust or correct the position of the user's foot while walking. It also can create awkward pressure points on the user's lower leg and/or foot as a result of the orthopedic device being urged unnaturally against the user's lower leg and/or foot while walking.
There exists a need for improved outsoles for orthopedic devices that facilitate a more natural and comfortable roll-over motion of a user's foot from heel strike through toe-off.